Control system for liquid heaters



Oct. 3l, 1939.. H. J. LONG |=:r Al. v

CONTROL SYSTEM FOR LIQUID HEATERS Filed Sept. 25, 1937 SOR. Q m N .A AwMw fw ML MJ N m -uw 7% mw N@ 1 m @XN .Y Q NN. K S km 7% nmw@ .w N\ W 2 NPatented Oct. 31, 1939 UNITED STATES CONTROL SYSTEM FOR LIQUID HEATERSHerbert J. Long and Edwin E. Vincent, SpringelsLMass., assignors toAmerican Bosch Corporation, a corporation of New York Appiitationseptember 25, 1937,1seria1No. 165,625

3 Claims.

rIhis invention relates to a fuel control system and more particularlyto a system for controlling the flow of gas to an instantaneous typewater heater.

In water heaters of this type as heretofore constructed, a piston orother movable element was exposed to the pressure in the waterline andconnected to actuate a valve in the gas line in accordance withVariations in the pressure or rate of flow of the water.

In all such arrangements, however, some movable member was subjecteddirectly to the pressure of the water, and therefore it was necessary tomake this member of `rugged construction and of materials which wouldnot corrode. Even when so constructed, solid matter deposited from thewater upon the movable member or upon surfaces in contact therewithwould occasionally cause the `member to stick and if such stickingoccurred when the gas valve was in open position, gas would continue tobe supplied to the burner even though no water was being withdrawn fromthe system. Such failures were of course ruinous to the heating element.These constructions also involved` wearable moving parts, andparticularly stuffing boxes, which are a constant source of trouble dueto leakage and friction.

It is a primary object of the present invention to avoid the abovementioned defects and provide a control system for instantaneous typeYheaters in which a control member opens or closes a valve for supplyingfuel to `a burner in response to the flow of water through the heater jbut in which there is no moving part subjected to the pressure. orcorrosive effect of the water.

It is a furtherobject of this invention to provide a device of this typewhich is of simple construction and which therefore can be easilymanufactured at a relatively low cost.

To these ends the invention provides for the creation of a`sub-atmospheric pressure in a medium such as air by an injector effectof the water owing through the system when a hot water tap is openedwithout the interposition of moving parts in or exposed to the water andthe utilizationk of this negative pressure for controlling the actuationof a fuel supply valve.

The above and other objects and features of the invention will b-eapparent to those skilled in thewart from a considerationA of thefollowing detailed description taken in conjunction with theaccompanying drawing, in which:

Fig. l is a View partly diagrammatic of the fuel control system appliedto an instantaneous is provided in the intake connection 2 but which may`be positioned at any point in the water line as convenient, is providedwith an internally" threaded bore 6 adapted to accommodate an externallythreaded plug 1. The plug 'ly is adapted to close the bore 6 except fora Venturi throat 8 which extends longitudinally through the plug I andflares sharply toward the intake end of the fitting 5 and expandsgradually in the opposite. direction, that is toward the discharge endof the fitting 5. p At a point which is slightly toward the dischargeside of the `most contracted portion of the throat 8, a lateral passage9 extends from the passage 8 to an annular chamber I formed by a groovein the periphery of the plug l. A lateral passage II in the fittingprovides communication between the annular chamber I0 and a check valvehousing I2. The housing I2 is provided with an externally-threaded endportion I3 adapted to o be inserted in an internally-threaded annularboss I4 surrounding the passage I I and a passage I5 in the housing I2provides communication between the passage Il and achamber I6 in thehousing. Acap I'I provides a closure for the chamber I6 and alsoprovides a bore I8 forming a guide for the stem I9 of a check valve 20.The check valve 20 normally rests on an annular seat 2l and when soseated closes Comunication between the chamber I6 and a chamber 22formed in the housing I2 immediately below the valve i 20. A smallpassage 23 provides a vent between the chamber 22 and the atmosphere anda passage 24 provides communication between the chamber 22 and a tube 25which is connected to the housing I2 by means of a nipple nut 26. Thetube 25 is connected by suitable nipple 21 and nut 28 to the upperportion of a diaphragm chamber 29. The chamber 29 is formed by twocupshaped housing members 30 and 3| which are provided with opposedperipheral flanges 32 and 33 between which a diaphragm l34 of flexiblematerial is adapted to be clamped and held by screw bolts 35. The upperhousing member 3U has a central opening 36 adapted to slipy over anannular boss 31 extending from a gas valve housing 38. The boss 31 isexternally threaded and a nut 39 is adapted to clamp the housing 30securely to a flat shouldered surface 4D provided on the housing 38surrounding the boss 31. The housing 38 is provided with a suitableinlet connection 4l and a discharge connection 42. A partition 43 havingan opening 44 provides a communication between the intake and dischargesides of the housing. A valve 45 is adapted to normally close theopening 44 and a stem 46 extending through a lateral bore 41 in thehousing 38 is connected to the diaphragm 34.

In the operation of the form above described, assuming that any tapconnected with the discharge connection 3 is open, water flowing throughthe Venturi throat 8, so that regardless duction in pressure in thelateral passage 9. This reduction of pressure causes the valve `l2 toopen and thus reduces the pressure in the chamber immediately below thevalve and like- Wise in the upper portion of the diaphragm chamber 29 towhich it is connected. The reduction in pressure in the chamber 29causes the diaphragm 34, which is exposed to atmospheric pressure on itsopposite side, to rise opening the main gas valve 45. Gas now flows tothe main burner 4, is ignited by a pilot 48 adjacent thereto, and thewater flowing through the heating element l is heated. The quantity ofgas will be proportionate to the rate of flow of water through theVenturi throat 8, so that regardless of the rate of flow the water willbe heated to approximately the same temperature, whether a large or asmall quantity of water is being withdrawn. It will be obvious that asmall drip or leak at the hot water tap will be insufficient to producethe necessary suction at the Venturi throat and that in such cases nogas will be supplied to the burner. On closing of the hot water tap andthe consequent cessation of iiow through the heating element, thepressure in the lateral passage 9 rises to the same pressure as thatwithnthe Water line and this pressure closes the check valve 28. Thepressure within the chamber 22 below the check valve is soon equalizedthrough the vent opening 23 and thus the pressure in the upper portionof the diaphragm chamber 29 soon equals the atmospheric pres sure towhich the lower side of the diaphragm is exposed. The diaphragm fallsclosing the gas valve 45 cutting oi the ow of gas to the burner. It willthus be seen that the invention provides a structure in which the valveactuating mechanism is not subjected to the pressure within the Waterline and is subjected only to a fluid pressure equal to or belowatmospheric pressure.

The form of the invention shown in Fig. 2 is similar to` the abovelexcept that the vent 55 is not continuously open. A valve l attached toa check valve 52 is raised upon the opening of the check valve inresponse to the suction in the passage 53 to close the vent orice 5D andtherefore maintain a higher degree of vacuum in the upper portion of thediaphragm chamber than would otherwise be the case. Upon closure of thecheck valve, the vent is open thereby providing a relatively large ventorice which permits immediate equalization between the pressure in thediaphragm chamber and the diaphragm and thus effects an immediateclosure of the valve controlling the supply of gas to the main burner.

The above description of the invention will be suilcient to enable thoseskilled in the art to vconstruct and use the same and to make variousembodiments and modifications thereof within the scope of the appendedclaims.

Having described the invention, what is claimed as new is:

l. A water heater including a burner, an element heated by said burner,connection for the supply of liquid to and the discharge of liquid fromsaid element, a chamber containing a fluid other than said liquid, atube forming a connection between said chamber and one of said liquidconnections and means whereby the flow of liquid through said connectiongenerates a reduction in the pressure of the fluid in said tube and saidchamber, a check valve in said tube for preventing the entry of saidliquid to said fluid chamber, and means responsive to the pressurevariations in said chamber between atmospheric and sub-atmosphericpressures for controlling the flow of fuel to said burner.

2. A water heater including a burner, an element heated by said burner,a water line in which said element is connected, an air chamber, meansincluding a venturi in said water line and a tube connecting saidventuri and said air chamber for creating a sub-atmospheric pressure insaid air chamber by means of the flow of liquid through said water line,means responsive to the pressure variations in said air chamber betweenatmospheric and sub-atmospheric pressures for controlling the flow offuel to said burner, a check valve in the tube connecting said airchamber and water line, an air vent in said air chamber, and a Valveconnected to said check valve for controlling said vent.

3. A water heater including a burner, an element heated by said burner,connections for the supply of liquid to and the discharge of liquid fromsaid element, an air chamber, means for creating a sub-atmosphericpressure in said air chamber in response to the flow of liquid throughsaid element, means responsive to the pressure variations in said airchamber between atmospheric'and sub-atmospheric pressures forcontrolling the iiow of fuel to said burner, means for preventing theflow of said liquid to said air chamber, and a vent in said air chamber.

HERBERT J. LONG. EDWIN E. VINCENT.

